1. Field of the Invention
The present teachings relate to methods of depositing or incorporating alkali metals, especially sodium onto the surface of a supported catalyst material while maintaining the physical stability of the catalyst.
2. Discussion of the Related Art
The use of sodium as an activator or modifier of catalyst performance or characteristics is known. A common sodium precursor utilized in catalyst preparation is sodium hydroxide. When dissolved in water, sodium hydroxide dissociates and produces a basic solution, and the hydroxyl ions can attack and destabilize catalyst binding agents, such as, silicate. The exposure to the basic solution can result in a destabilized catalyst structure which can result in the catalyst falling off of the substrate.
Additionally, sodium components on a catalyst can usually be washed off the catalyst when exposed to aqueous impregnation solutions. One typical approach to this problem is to increase the initial sodium loading to compensate for the loss due to exposure to the subsequent aqueous impregnation solutions.
A need exists for a method of depositing or incorporating sodium into a catalyst formulation while maintaining the physical stability of the catalyst and its support or substrate.